Quantum Well Semiconductor Phosphor for Narrow Red Emission
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Solution Overview
Problem
Conventional semiconductor phosphors face challenges in efficiently changing light wavelength, particularly in producing RGB-based white LEDs with narrow emission spectra, as they often emit broad red spectra and have difficulty controlling wavelength, especially in the near red region.
Innovation Solution
A semiconductor phosphor structure comprising at least one active layer made of a compound semiconductor with an n-type or p-type dopant and alternately stacked barrier layers, which are also compound semiconductors with a larger band gap, enhancing wavelength changing efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional phosphors (YAG type, SiAlON type, CASN) are used to change blue light wavelength, then light wavelength changing is achieved, but the emission spectrum becomes broad and wavelength control becomes difficult
Solution Approach 1:
The phosphor is segmented into multiple quantum well layers (active layers and barrier layers) with different band gaps. Each layer segment contributes to a specific wavelength range, allowing precise control of the overall emission spectrum by adjusting the number, thickness, and composition of individual layers. This segmentation enables narrow full width at half maximum (FWHM) while maintaining high wavelength changing efficiency.
Solution Approach 2:
Different regions of the phosphor structure are assigned different local properties: active layers with smaller band gaps for light emission at specific wavelengths, and barrier layers with larger band gaps for confining carriers. The composition and thickness of each layer are locally optimized to achieve the desired emission characteristics, enabling precise wavelength control and narrow emission spectra.
2Manufacturing precision
If quantum dot is used for wavelength changing via quantum size effects, then wavelength adjustment is possible, but size dependency is large and fluorescent wavelength control becomes difficult
Solution Approach 1:
Instead of controlling wavelength through quantum dot size (which has large size dependency), the invention changes the wavelength by adjusting the composition parameters (Al, Ga, In ratios) and thickness parameters of the semiconductor layers. This approach reduces sensitivity to dimensional variations and provides more controllable wavelength tuning through compositional adjustments in the (AlxGa1-x)yIn1-yP system.
3Loss of energy
If compound semiconductors are stacked with separate light-receiving and light-emitting parts, then wavelength changing is achieved, but light emission efficiency is insufficient
Solution Approach 1:
The invention merges the light-receiving and light-emitting functions into the same quantum well structure. The active layers absorb incident blue light and simultaneously emit converted light at longer wavelengths through photoluminescence. This merging eliminates the inefficiencies of separate light-receiving and light-emitting parts, achieving high light emission efficiency while maintaining a relatively simple stacked layer structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This structure allows for high efficiency and stability in wavelength adjustment, achieving a sharp emission spectrum compared to conventional phosphors, particularly effective in changing blue light to red with improved light emission efficiency.
Implementation Method 1
a semiconductor phosphor configured to exhibit photoluminescence upon irradiation with excitation light
Implementation Method 2
at least two barrier layers made of a compound semiconductor and having a larger band gap than the active layer
Data Source
AI summary
A semiconductor phosphor configured to exhibit photoluminescence upon irradiation with excitation light, including: at least one active layer made of a compound semiconductor and containing an n-type or p-type dopant; and at least two barrier layers made of a compound semiconductor and having a larger band gap than the active layer. The active layer and the barrier layers are alternately stacked. This provides a semiconductor phosphor which allows easy wavelength adjustment, high efficiency and stability.